/// <summary>
/// Finds variables that were assigned to and determines their types.
/// </summary>
/// <param name="root"> The root of the abstract syntax tree to search. </param>
/// <param name="variableTypes"> A dictionary containing the variables that were assigned to. </param>
/// <param name="conditional"> <c>true</c> if execution of the AST node <paramref name="root"/>
/// is conditional (i.e. the node is inside an if statement or a conditional expression. </param>
/// <param name="continueEncountered"> Keeps track of whether a continue statement has been
/// encountered. </param>
private static void FindTypedVariables(AstNode root, Dictionary <Scope.DeclaredVariable, InferredTypeInfo> variableTypes, bool conditional, ref bool continueEncountered)
{
if (root is AssignmentExpression)
{
// Found an assignment.
var assignment = (AssignmentExpression)root;
if (assignment.Target is NameExpression)
{
// Found an assignment to a variable.
var name = (NameExpression)assignment.Target;
if (name.Scope is DeclarativeScope)
{
var variable = name.Scope.GetDeclaredVariable(name.Name);
if (variable != null)
{
// The variable is in the top-most scope.
// Check if the variable has been seen before.
InferredTypeInfo existingTypeInfo;
if (variableTypes.TryGetValue(variable, out existingTypeInfo) == false)
{
// This is the first time the variable has been encountered.
variableTypes.Add(variable, new InferredTypeInfo()
{
Type = assignment.ResultType, Conditional = conditional
});
}
else
{
// The variable has been seen before.
variableTypes[variable] = new InferredTypeInfo()
{
Type = PrimitiveTypeUtilities.GetCommonType(existingTypeInfo.Type, assignment.ResultType),
Conditional = existingTypeInfo.Conditional == true && conditional == true
};
}
}
}
}
}
// Determine whether the child nodes are conditional.
conditional = conditional == true ||
continueEncountered == true ||
root is IfStatement ||
root is TernaryExpression ||
root is TryCatchFinallyStatement ||
(root is BinaryExpression && ((BinaryExpression)root).OperatorType == OperatorType.LogicalAnd) ||
(root is BinaryExpression && ((BinaryExpression)root).OperatorType == OperatorType.LogicalOr);
// If the AST node is a continue statement, all further assignments are conditional.
if (root is ContinueStatement)
{
continueEncountered = true;
}
// Search child nodes for assignment statements.
foreach (var node in root.ChildNodes)
{
FindTypedVariables(node, variableTypes, conditional: conditional, continueEncountered: ref continueEncountered);
}
}
